Safety evaluation and potential health implications of water from post-remediated lead-polluted areas of Zamfara State, Nigeria

Abstract

Objectives: Dareta village in Zamfara state of Nigeria is one of the villages plagued with the lead (Pb) poisoning crisis of 2010. Dareta and neighboring villages were remediated by simple excavation of topsoil rich in Pb, and burying same in landfills. This study was embarked to assess the physicochemical parameters of some sources of water supply and possible health impacts on humans. Material and Methods: The village was imaginarily mapped into three sites; Residential Homes (Site 1), Markets and Village Squares (Site 2), and Farms with Irrigation Facilities (Site 3). From the three sites, a total of 30 water samples (10 shallow wells, 10 boreholes, and 10 stream/surface water) were randomly collected, according to availability. The physical parameters (Temperature, Conductivity, and Total Dissolved Solids [TDS]) were assessed in situ using a conductivity/TDS meter (model 44600.00, HACH, USA), the assessment of pH was also carried out in situ using an electronic pH meter, (pH 210 micro-processor, Hanna Instrument, USA). The evaluation of heavy metals concentration (Pb, cadmium [Cd], chromium [Cr], and manganese) was done using an Atomic Absorption Spectrophotometer (modelAA-6800, Schemadzu, Japan). Results: In groundwater (boreholes and wells), the mean temperature and conductivity were higher than the World Health Organization (WHO) safety levels for “drinking water,” while those of TDS and pH were within the limits. In surface water (streams), the assessed physical parameters were not higher than the WHO safety limits, while the concentrations of Pb, Cd, and Cr were above the drinking water guidelines. The risk implication in the human populations consuming the water was determined using the estimated average daily intake (EADI) and the target hazard quotient (THQ). The EADI for Pb, Cd, and Cr for all the water sources in both adult and children consumer populations exceeded the reference dose by US-EPA. The THQ for Pb, Cd, and Cr in both adult and children consumer populations were >1. Conclusion: These findings portend toxicity and increased hazards for the human populations that source their drinking water from the borehole, well, and stream in this village.